Hi!
I have just bought a 2012 carbon iSonic 137 for light wind leisure sailing and I need some help on choosing the right size of sail to match it.

Iím not into racing, but I want to go really fast and do long distances including hi upwind courses (as hi as a slalom board can point Ė I didnít want a formula).

I weight about 73 Kg and during the last years Iíve been using a 2009 JP freestyle Wave 107 board matched with NeilPrydeís 2009 Firefly 5,7 and Hellcat 7,2.
With the Hellcat 7,2 Iím able to sail really well (consistently into the footstraps and planning) with wind of about 16 Knts (30 Km/h) and above.

I also got a 2010 Starboard Go 155 to teach my kids and friends, which I also intended to use my self for lighter winds (lighter than 16 Knts), but it doesnít seem to do much difference: about 15 Knts (28 Km/h) is the threshold to have really good time (consistently into the footstraps and planning) (with the Hellcat 7,2).
Recently I once also tried the Go 155 with a NeilPryde V8 8,5 (I think of 2009 make), but it was rigged with an X3 mast (only 35% carbon), it felt quite heavy and didnít seem to do much difference in terms of early planning (at least not the difference I expected or rather wanted).
I suppose it also has to do with the shape and mainly the weight of the Go 155: almost 12 Kg.

So now I got the 2012 carbon iSonic 137 and Iím thinking of buying the 2013 NeilPryde H2 racing to match it (8 batten-2 cam ďfreeraceĒ sail).
Basically I want to use the iSonic 137 for winds of about 15 Knts and less. (for stronger winds Iíll be using my freestyle Wave 107).
I donít know if the iSonic 137 will work well with my existing Hellcat 7,2 (no-cam ďfreeraceĒ sail) at say 15-13 Knots of wind.
I will only buy one new sail (almost decided for the H2 racing) and I canít decide which size: 8,7 or 9,3?
The objective is to constantly plane from into the footstraps with the lowest possible wind but without living any gaps (wind range for which I wonít have a good combination of board-sail with all the gear I will have).

Hi mcross19,
Thanks a lot for your recommendation.
My only concern about choosing the 8,7 instead of the 9,3 is that according to NeilPryde's general wind-range-chart
(the chart that shows all the sails together - not the chart on H2's page which differs a bit and I suppose needs updating)
the low-end threshold of 8,7 H2 is not much different from that of 7,2 Hellcat, only 2-3 knts of wind (8,7 H2 starts at about 8 knts, while 7,2 Hellcat starts at 10-11 knts).
If you can, please have a look at NeilPryde's chart and verify or not your initial recommendation (for the 8,7) - it would be much appreciated.
Thanks a lot anyway,
Regards
Neo

At 73Kg he is unlikey to want anything in the 10m+ sail size aslo he has said that it will be his one and only sail purchase so H2 8.7 or Severne Turbo 8.6 is perfect considering his next sail down is 7.2. 9.3 down to 7.2 is quite a big jump but is do-able.

Agree with most comments above but I strongly doubt you will be able to plane as of 8 knots with an 8.7 sail at 73 kg. I guess the NP chart is kindda off the mark on this case because I cannot do it for sure in real life.

Do not dismiss the 3 knots difference between 7 and 10 knots of wind as not significant. On the contrary, this is a huge difference in fact. The lighter the wind, the more sail surface you'll need to start and sustain the planing with your big board. BTW, the planing difference between an 8.5 and a 9.5 sail is about 1 knot earlier. That is small in absolute term but it is plenty enough to be able to plane with a 9.5 sail whereas you will shlogg with an 8.5 sail if the wind is just too light for you.

Since the iSonic 137 is really a big board for your medium weight, I would strongly suggest you to use the H2 9.3 m2 sail (or something larger) if you really want to maximize its low range of usage. For the record, I've tried my 11 m2 sail + 55 cm fin on an iSonic 127 carbon 2011 and it was flying upwind and downwind without any problem as of 7 knots of wind.

However, the main concern that I have for you is I fear that your sail of 7.2 m2 is quite a bit too small on such a big board for your relatively light weight (iSonic 137 is mainly designed for 95+ kg rider for PWA slalom) and I doubt it will be an efficient combo when the wind is strong with some serious chop. You can try with the 7.2 sail and a small fin, but do not expect some miracle control and handling...

I know a lot of people will disagree with me, but I wonder if you would be better looking at the Futura instead of the iSonic!!!

Yep the iSonics will work with performance freeride sails and freerace sails, and I see lots of people using these type of sails on iSonics and they are having a great time, but they are not really going faster than good freerace boards.

To be 100% truthful, iSonics are really designed to be sailed with full race sails in over-powered conditions. This something that freeride/freerace sails don't do as well as full race sails. In over powered conditions, iSonic become alive, fast and fun.

In most 6m or 7m freerider or freerace conditions it would be correct to take an 8.5/9m sail on an iSonic. Not every ones idea of fun, but thats how iSonic like it.

And I agree with Jean-Marc, a 7.2m on the iS137 is not good. 8.5m is really the smallest you should go.

Hi, I (98kg) sail the 137 with NP evo 9.5 / 8.6 / 7.8 in competition. Board is great with 9.5 (with 51cm or even 54 cm fin), and oke for me with 8.6. When wind is suitable for 7.8 I rather change to the 107 and 7.8.

My advice, as you already bought the 137: buy the 9.3 or better a 9.5 racesail.